Safety device for power-take-off shafts



Feb. 21, 1933. W, zlNK 1,898,113

SAFETY DEVICE FOR PQWER TAKE-OFF SHAFTS Filed Jan. 25, 1932 Patented Feb.21`,19ss 1,893,113v

UNITED STATES? PATENT oFFlcE;

WILLIAM L, ZINK, .OF AURORA, ILLINOIS SAFETY DEVICEFOR POWER-TAKE-OFF SHAFTS Application led January 25, 1932. Serial No. 588,801.

In connection with the use of tractor illustrated in the accompanying drawing, drawn plows and the like, it is customary to in which: provide-a draw bar connection between the Figure 1 shows a side elevation of portions two implements, so arranged that when, for of a tractor and an implement such as a plow 5 instance, the plowsliould strikefa heavy obwith a draw bar connection and a power- 55 struction, or, for various other reasons, the take-off device embodying my invention. draw bar will disconnect from the tractor to Figure 2 shows an enlarged, detail,iside eleprevent injury to the implements. vation illustrating a portion of thepowerl/Vhen a pulverizer attachment is used on take-off shaft, kthe forward universal joint 10 the plow, such for instance as that disclosed and a portion of the slip tube connected with 60 in the patent to Davidson, Number 1,697 ,679, the universal oint, and illustrating `my imissued January1,'1929, then it is necessary to proved spring release device forpermitting provide a connection between the powera separation` between the po'wer-ta-ke-off take-off `of the tractor and the power Lshaft shaft and the forward universal joint.

l5 of the pulverizer attachment through which Figure 3 shows an enlarged, detail, sec- 65 power can be transmitted vfrom theftractor 'tional view illustrating the adjacent ends of tothe pulverizer, and vobviously there must the friction release means between the for; be means for permitting this power shaft ward and rear portions ofthe draw bar. connection to become separated just like the Y Figure Li shows a` sectional viewA on the o draw bar when the plow meets a heavy obline 4 4 of'Figure 1; and

struction. Figure 5 shows a sectional view onthe line Heretofore with devices of this kind it has 5-'5 of Figure et, ebeen found that when the power shaft con- Referring to the accompanying drawing I nection becomes separated, the end thereof have used the reference numeral 10 to indiadjacent to the tractor will, when the powercate that portion of Va tractor shown.V This 5 takeoff is rotated, move to a position subtractor is provided with a power-takeoff stantially at right angles to the power-takeshaft 11, the. rear end of which is'preferably off shaft on account of centrifugal action squared at 12 and infront of the squared porand rapidly whirl about and injure the tion there is lined a collar 13. The sliptube 0 mechanism or an operator. 14 of the power shaft is provided at litsforso rl'Che object of my invention is to provide ward end with a. universaljoint member 15 a power-take-off device for use in transmitand a coacting universal joint memberzl'is ting power from a tractor to an implement connected with it in the ordinary manner.

9 such as a pulverizer attachment for plows, At the forward end of the universal joint "5 so arranged that when the draw bar between member 1G is a socket 17 having a squaredin- 5 the plow and the tractor becomes separated, terior to slidingly and non-rotatively receive all that portion of the power shaft in the the squared portion 12 of the rpower shaft.l rear of the front universal universal joint Carri-edY by the universal joint memberl thereof will become disconnected from the are 4two spring retaining arms, indicated power-take-off shaft and be carried by the generally by the numeral 18: Near the 'fordriven implement, so that in the event that ward ends thereof: arel the inwardly and the power-take-off shaft should continue to slightly forwardly inclined shoulders 19, and rotate after the draw bar has been disconat the forward ends thereof'are the outwardly nected, it would not have any injurious efand forwardly inclined shoulders 20; y, fects. lnoperation with this part of the device, 95 My invention consistsv in the construction, when the universal joint member 16fis moved arrangement and combination of the various forwardly, the squared portion 12 enters the parts of the device, whereby the objects consquared socket 17, and at the same time the templated are attained, as hereinafter more inclined shoulders 2O are forced apart by the i fully set forth, pointed out in my claims, and collar 13 until the collar is in the rear. of the 100 inclined shoulders 19, whereupon these arms 18 spring together and frictionally hold the collar within the spring arms against separating movement, except when excessive strain in a rearward direction is applied to the slip tube, and when this occurs, the pressure of the collar against the inclined shoulders 19 causes the spring arms to separate.

Slidingly inserted in the rear end of the slip tube is an angular slip shaft 21 formed with a longitudinal groove 22, which groove terminates at its forward end a short distance in the rear of the front end of the slip shaft, forming a shoulder 23. After the slip shaft is inserted in the slip tube, I insert a set screw 24 through the slip tube and into the groove 22, thus permitting a free movement of the slip tube within the slip shaft, which movement, however, -is limited to prevent the complete withdrawal of the slip shaft from the slip tube.

At'the rear of the slip shaft is a universal joint 25, and at the rear of this universal joint is the power shaft 26 for the pulverizer attachment or other implement to be driven. The plow or other implement is provided at its forward end with a clevis 27, and pivotally connected to this clevis is a draw bar member 28 to connect with a draw bar member 29 pivoted to a portion of the tractor 30. The two portions of the draw bar are connected by a hitch pin 31 and the draw bar is provided with a friction joint, which consists of two members 32 and 33, spaced apart and provided with bolts for drawing them together, and a member 34C having a slot 35 and designed to be inserted between the members 32 and 33 and to be frictionally secured therein by said bolts.

In practical operation, and assuming that the implement being drawn by the tractor should strike a heavy obstruction, then the two members of the draw bar will separate in the ordinary manner, and when this is done, then the entire strain of the tractor will be thrown upon the lslip tube, after the limit of the movement between the slip tube and the slip shaft has been reached. When this vheavy strain is thus applied to the slip tube, then the inclined shoulders 19 of the spring retaining arms will be caused to separate enough to permit the arms 18 to spring apart far lenough to clear the collar 13, where-V upon the entire slip tube and slip shaft device will drop away from the power-take-off shaft, and hence even if the power-takeoff shaft should continue to rotate, there will be no injurious effects.

I claim as my invention:

1. In a device of the class described, the

`combination of a power-take-of shaft, a slip tube and a slip shaft slidingly connected, means for limiting the movement of the slip shaft out of the slip tube, a universal joint at the forward end of the slip tube, and means operated by an excessive pull upon the slip tube to disconnect it from the power shaft, said means comprising a squared socket formed on the forward end of the universal joint, a squared rear endportion on the powertake-off shaft to enter said socket, a collar fixed to the power-take-of't1 shaft, and spring retaining arms fixed to the universal joint to engage the said collar and normally hold it against separating movement relative to the spring arms, said spring arms being so shaped that excessive vpull applied to the slip tube will permit the spring arms to separate and release the collar.

2. In a safety device for power take 0E shafts, the combination of a power take off shaft, a driven shaft, a universal joint at the forward end of the driven shaft, the adjacent ends of said shafts being slidingly and non-rotatably connected whereby when con- 'nected the driven shaft may be rotated by the v"power shaft, and when the driven shaft is moved rearwardly it will be disconnected from the power shaft, and a two part spring latching device, one part carried by the powi.

er shaft and the other by the driven shaft, said spring latching device including shoulders for normally gripping the other latch member and for releasing it upon an excessive pull rearwardly upon the driven shaft. i515 Des Moines, Iowa, December 17, 1931. WILLIAM L. ZINK. 

